After an autopsy was performed on “Happy Days” star Erin Moran, authorities have determined that the “likely" cause of her death is stage 4 cancer.

Now, Erin Moran’s husband Steven Fleischmann has written an open letter about her sad passing, posted to Facebook by Moran’s former co-star, Scott Baio.

In the letter, Fleischmann wrote, "The coroner told me it was really really bad. It had spread to her spleen, she had alot of fluid in her lungs and part of her brain was infected. The coroner said even if she was in the hospital being pumped full of antibiotics she still would not of made it. He said it was the best that she was with me and went in her sleep.”

Steven recalled, "She woke up on the 22nd, she was not 100%. She needed Kleenex, so i went to the store and came back. She was there watching T.V in bed. I laid down next to her held her right hand in my left. I feel asleep woke up about a hour later still holding her hand and she was gone, she was just gone.”

At the end of November, one of the first troubling signs of Erin's cancer battle was “a dime size blood strain” on her pillowcase. In December, she went in for a biopsy, which determined that she had a “squamous cell carcinoma.” Fleischmann wrote, “She started radiation and chemo… it got so bad so fast. By the middle of February, Erin could no longer speak or eat or drink. She had a feeding tube implant and I feed her 6 to 8 times a day.”

Just a day before dying, Erin was already “having trouble breathing.”

Despite her struggles, Steven emphasized, “She was still happy, she was active, she texted people on her phone all day.”